Means for indicating defects in thread



May 20, 194.1. y E. A. KEELER l I 2,242,890

MEANS FOR. INDICATING DEFECTS IN THREAD Original Filed Dec. 29, 1936 FIG. l.. l

28 f 32 l Z0 v FIG. 3. L2" rl.'

FIG. 2. 2X l2 32 26 22 l /S//l/' 24 9 fis/swf INVENTOR. EARL A. KEELER ATTORNEY.

` is transferred from one spool to another.

Patented May 20, 1941 MEANS FOR INDICATING DEFECTS IN THREAD Earl A. Keeler, Norristown, Pa., assignor to The Brown Instrument Company, Philadelphia, Pa., a corporation of Pennsylvania Original application December 29, 1936, Serial No. 118.095. Divided and this application April 9, 1938, Serial No. 201,130

4 Claims.

This invention is directed to apparatus responsive to variations in a condition and including a space discharge device adapted to be actuated by variations in said condition.

The present invention is a division of my prior application Serial No. 118,095, led Dec. 29, 1936, now issued into Patent 2,188,754, which discloses various arrangements for detecting defective filaments in athread together with means actuated thereby for indicating and/or recording the number of such imperfections.

The various arrangements disclosed in my prior application were devised by me with the general object in view of providing simple and efcient means for detecting defective filaments in a single thread or in a plurality of threads together with means actuated thereby for indicating the presence and/or recording the number of such other threads the presence of defective filaments in the individual threads shows up in the finished material in the form of fuzzy ends. Heretofore in order to eliminate these fuzzy ends provisions have been made for the inspection by observation of a portion of the thread during transfer of the thread from spool to spool and rejection of any spools having an excessive number of defective filaments. This inspection operation is obviously expensive and, more important from the standpoint of producing quality material, is inadequate by virtue of the fact that only a small portion of the total output can practicably be inspected.

Moreover, visual inspection of the thread during transfer of the thread from spool to spool and detection of defective filaments is diicult as will be readily appreciated when it is understood that rayon threads which themselves are eX- tremely small in diameter are made up from 40 to 100 or more of such filaments. By means of the arrangement claimed herein, the manual inspection operation referred to may be dispensed with and defective thread filaments may automatically be detected and indicated by readily distinguishable means. tomatic detection, I employ a delicate switch member arranged in the path of the thread which is actuated when'engaged by the fuzz or defective filaments of the thread as the thread As a means for such aupacts of the moving fuzz'projections on the delicate switch member, which has little inertia, result `in the closure of a contact and thereby in energization of a suitable indicating means to be described. Thus an indication of the presence of defective filaments of the thread, which are diiiicult of detection by visual means alone, is had.

The various features of novelty which characterize my invention are pointed out with particularity inthe claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages and specific objects obtained with its use, reference should be had to the accompanying drawing and descriptive matter in which I have illustrated and described the best form of my invention now known to me.

Of the drawing:

Fig. 1 is a more or less diagrammatical View illustrating one form of my invention;

Fig. 2 is an end elevation of the contacting switch member shown in Fig. 1, shown as viewed in the direction of the arrows 2 2 of Fig. 1; and

Fig. 3 illustrates a modification of the arrangement of Fig. 1.

Referring to Fig. 1, provision is made, as illustrated, for arranging a detector I in the path of the moving thread for detecting the presence of defective filaments in the thread. Normally in practice, the detector may desirably be arranged in the path of the thread as it is being unwound from a spindle on a spinning machine and wound on a bobbin immediately after the spinning operation. For clarity and definiteness of illustration, however, I have shown', in a more or less diagrammatic way, the thread 2 as being unwound from a spool 3 and reeled on a spool 4, the latter being mounted for rotation on a shaft 5 driven through suitable gearing, not shown, by a unidirectional electrical motor 6 energized for rotation from alternating current supply lines L1 and L2. Thespool 3 is mounted for rotation on a shaft 'I which may be disposed on suitable brackets 8 in any convenient manner. Preferably both spools 3 and 4 are so mounted for rotation as to facilitate quick removal and replacement by others`pools.

The detector l is a delicate switch mechanism including a contact arm 9 pivoted intermediate its ends for rotation on a light suspension wire I0, which may be of phosphor bronze or other suitable material, and disposed in the path of the thread. As best seen in Fig. 2, wire l0 is suspended between opposite arms of a U-shaped member Il at the upper ends thereof. rIfhe arm I latter.

9 is provided at its upper end'with a bifurcated portion or stirrup I2 which is so arranged that one arm of the stirrup is disposed on either side of the thread. The arms of stirrup I2 are separated by a distance slightly greater than the normal diameter of the thread so that any proright angles to the arm 9 and securely fastened at' one end to a stationary rod member I4 which may be mounted in any suitable manner as for eX- ample on the rod I5. As defective filaments strike the stirrup I2 and rotate the arm 9 into engagement with the exible contact I3, the suspension wire I sets up a resisting torque to thereby return the arm 9 to its normal position when the fuzz projections on the thread have passed on. The thread is guided into the stirrup I2 by guide rods I5 and I6 having saddle portions at their upper end for guiding the thread. The resiliency of contact I3 permits movement of the arm 9 to any position which may be taken by the This is important to prevent injury to the thread or detector in the event that a knot or other unusually large projection from the thread engages the stirrup I2.

, When the contacting arm 9 is rotated into engagement with the exible Contact I3, a circuit including the contacts will be completed for operating a'cathode ray tube I'I for indicating the presence of the defective' filaments in the thread which caused the movement of arm 9 into engagement with contact I3. The cathode ray tube I 1 employed is comprised of the usual elements; a cathode I8, an anode I9 having a small aperture in the center thereof to permit a stream of electrons to pass through, a pair of deflecting plates 20 and a uorescent screen 2l. A suitable direct current potential is maintained on the anode by a battery I 9 and current is supplied for heating the filament by a battery i8. A continual stream ,of electrons passes from the cathode I8 to the anode I9 some of which pass through the small opening or aperture in the anode and due to their high velocity normally travel in a straight line through the deecting plates 29 to the screen 2I the latter becoming luminescent at the point at which the electrons strike. When an alternating current voltage is applied to the deilecting plates 20 the electron stream will be deected iirst in one direction and then the other at the frequency of the applied alternating-current "voltage resulting in a luminescent line appearing on the screen 2I. According to my invention I apply an alternating voltage to the delecting plates 20 whenever defective thread filaments strike the stirrup' I2 and thereby bring the arm 9 into engagement with the flexible contact I3.

The means by which the alternating current voltage is applied to the deflecting plates 20, as

illustrated by Fig. 1, include two heater typethree-electrode electronic tubes 22 and 23 lin- 'cluding the` usual anodes 24 and 25, grids 26 and 2'I and cathodes 28 and 29, respectively. The anode to cathode resistances of valves 22 and 23 are connected in opposite arms of a Wheatstone bridge network, the two remaining arms of the bridge consisting of equal resistances 3I|A and 3|, the latter being connected to cathodes 28 and 29 are connected through a grid biasing resistor 32A to the alternating current supply lineLl. Thev deflectingplates 20 of the cathode ray tube are connected between the anodes 24 and 25 on which equal potentials are maintained when the bridge is balanced so that normally both of the deflecting plates are at the same potential and the electronic stream is permitted to pass through them undisturbed. The grids 26 and 21 are connected tothe alterhating current supply line L1, the grid 26 being connected thereto through a one-megohm resistor 33. The grid 26 is connected also to the ilexible contact I3 by a conductor 34 and the contacting arm 9 is connected by a conductor 35 to the cathodes 28 and 29. The resistor 32 provides a negativeqbias for both grids 26 and 21 so that both tube's"22 and 23 normally are equally conductivejz, Upon engagement of the arm 9 with the flexible contact I3 resulting from defective thread filaments striking the stirrup I2, however, the grid 26 is connected directly to the cathode 26 and the potential thereon is raised to that of the cathode-potential whereupon the resistance of tube 22 to the flow of anode current decreases and the bridge becomes unbalanced. Since lthe current supplied to the bridge by the supply lines L1 and L2 is alternating, the currents conducted by thetubes 22 and 23 will be pulsating and bridge unbalance will result in an 4alternating voltage being applied to the deiiecting plates 20. This alternating voltage on the plates 20 deflects the cathode ray stream in a manner hereinbefore described and a luminescent straight line appears on the fluorescent screen 2|. Such visual indication is had each time that defective thread filaments strike the stirrup I2 of the 'delicate switch mechanism I.`

If desired, the tube 23 and resistor 3I may be dispensed with and the plate 20 which is connected to this side of the bridge may be connected directly to the supply line L1, as illustrated, more or less diagrammatically, in Fig. 3. An alternating voltage will then be continuously applied tothe deilecting plates 20 resulting in the appearance of a luminous line on the uorescent screen 2I, but the length of this line will be varied when the contacting arm 9 engages the flexible contact I3 to thereby indicate the presence of thread imperfections.

While in accordance with the provisions of the statutes, I have illustrated and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled yin the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of my invention as set forth in the appended claims, and that certain features of my invention may sometimes be used to advantage without a corresponding use of other features.

Having now described my invention, What I claim as new and desire to secure by Letters Patent is:

1. In apparatus for detecting defective laments in a thread, a normally balanced Wheatstone bridge comprising a pair of electronic valves in two opposite arms Athereof and similar resistances in the remaining arms, ythe said electronic valves each comprising an anode, grid and a cathode, a source of alternating current voltage for said bridge, a cathode ray tube comprispair of deecting plates, said deflectingplates being connected across the balancing connections of said bridge, a source of direct current voltage for said cathode ray tube, detecting means disposed in cooperative rel-ation with said thread adapted to detect said defective laments, and means for relatively moving said thread and detecting means adapted under control of said defective filaments to vary the flow of anode current through one of said electronic valves.

2. In measuring apparatus, a normally balanced Wheatstone bridge comprising a pair of electronic valves in two opposite arms thereof and similar resistances in the remaining arms, the said electronic valves each comprising an anode, grid and a cathode, a source of alternating current voltage for said bridge, a cathode ray tube comprising a fluorescent screen, anode, cathode, and a pair of deecting plates, said defiecting plates being connected across the balancing connections of said bridge, a source of direct current voltage for said cathode ray tube, detecting means disposed in cooperative relation lwith a variable to be measured, and means `unsaidelectronic valves each comprising an anode, grid and a cathode, a source of alternating current voltage for said bridge, a cathode -ray tube including an anode and a cathode for producing an electron stream, and a 'pair of deecting plates controlling the direction of said stream, said deflecting plates being connected across the balancing connections of said bridge, a source of direct current voltage for said cathode `ray tube, detecting means adapted to detect a variable to be detected, and means controlled by said detecting means to vary the flow of anode current through one of said electronic Valves to thereby vary the potential impressed upon said deflecting plates and thereby to Vary the direction of said electron stream.

4. VApparatus for detecting defective filaments in a thread comprising a bridge circuit having a pair of electronic valves in two opposite arm-s, a source of alternating voltage for said bridge,

a detector disposed in operative relation with 

